Identifying and using bibliographical references in electronic books

ABSTRACT

An electronic book system recognizes patterns in texts that correspond to bibliographical references. User selection of a bibliographical reference causes a digital copy of the work referenced to be made available to the user. Factors such as price, reference format and user feedback are used to select a source from which the digital copy of the work is obtained.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 61/446,239, filed Feb. 24, 2011, which is incorporated by reference in its entirety as if fully set forth herein.

BACKGROUND

1. Technical Field

The invention generally relates to the field of electronic books and, more particularly, to systems and methods for accessing additional materials referenced within an electronic text via electronic devices.

2. Background Information

Even as widespread use of the Web reaches its twentieth anniversary, there has been little change in how people make use of textbooks. Students still fill their backpacks with as many of the five-pound books as will fit, and the impact of such paper-based learning is felt not only in students' backs, but in the carbon footprint of all of the infrastructure required to supply, use and dispose of such materials. A change of just a few pages in a textbook may make it obsolete and call for a new version to be printed; students carry not just this week's chapters with them everywhere, but last month's and next month's chapters as well.

Although some attempts have been made to transform study material from Gutenberg's era to the digital era, some of the advantages of using paper books for study purposes have not been replicated. Students from time immemorial have used their texts in different ways. Some highlight portions of particular interest; others place notes in the margins to keep track of clarifications of difficult concepts. Some used textbooks are more useful than new ones because they naturally fall open to the most important pages after repeated use, or because particularly important pages or sections are more dog-eared than others. Electronic reading devices have not to date provided some of these subtle yet important features that help students learn from their texts most efficiently.

It would be advantageous to provide improved mechanisms for students to obtain, read, study from and otherwise use textbook content with some of the tablet, laptop and other electronic devices that are now entering widespread use.

SUMMARY OF THE INVENTION

An electronic book reader system includes a recognition subsystem for identifying bibliographical references in an electronic book and an ordering subsystem that allows a user to obtain a digital copy of a referenced external work.

In some aspects, the ordering system automatically selects a preferred source for a referenced external work responsive to one or more factors, such as price, terms of use, format, a user's preferred vendor, and user feedback. In one such aspect, referenced works are obtained free of charge; in others, the user makes a payment. In one such aspect the system automatically divides and distributes portions of the payment made to two or more parties with a financial interest in the referenced external work.

Further, a method for providing an electronic book includes identifying bibliographical references in an electronic book and providing a digital copy of a referenced external work.

In some aspects of this method, a preferred source for a referenced external work is automatically selected responsive to one or more factors, such as price, terms of use, format, a user's preferred vendor, and user feedback. In one such aspect, referenced works are obtained free of charge; in others, the user makes a payment. In one such aspect the payment made is automatically divided and distributed to two or more parties with a financial interest in the referenced external work.

Still further, a computer program product includes computer instructions to identify bibliographical references in an electronic book and provide a digital copy of a referenced external work.

In some aspects of this computer program product, computer instructions are provided to automatically select a preferred source for a referenced external work responsive to one or more factors, such as price, terms of use, format, a user's preferred vendor, and user feedback. In one such aspect, referenced works are obtained free of charge; in others, the user makes a payment. In one such aspect the payment made is automatically divided and distributed to two or more parties with a financial interest in the referenced external work.

The features and advantages described in the specification are not all inclusive and, in particular, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings, specification, and claims. Moreover, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the disclosed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a high-level diagram illustrating a networked environment that includes an electronic book reader.

FIG. 2 illustrates a logical view of a reader module used as part of an electronic book reader.

FIG. 3 illustrates a logical view of a system database that stores data related to the content hosting system.

The figures depict various embodiments for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the invention described herein.

DETAILED DESCRIPTION Electronic Textbook System Overview

FIG. 1 is a high-level diagram illustrating a networked environment 100 that includes a book content hosting system 110. The embodiments discussed herein are particularly suited for textbooks, but one skilled in the art will recognize that many of the features discussed herein are applicable to various other types of books as well. The content hosting system 110 makes available for purchase, licensing, rental or subscription textbooks that can be viewed on user and content provider computers 180 (depicted in FIG. 1, for exemplary purposes only, as individual computers 180A and 180B) using a reader module 181 or browser 182. The content hosting system 110 and computers 180 are connected by a network 170 such as a local area network or the Internet.

The network 170 is typically the Internet, but can be any network, including but not limited to any combination of a LAN, a MAN, a WAN, a mobile, a wired or wireless network, a private network, or a virtual private network. The content hosting system 110 is connected to the network 170 through a network interface 160.

As discussed above, only a single user computer 180A is shown, but in practice there are many (e.g., millions of) user computers 180A that can communicate with and use the content hosting system 110. Similarly, only a single content provider computer 180B is shown, but in practice there are many (e.g., thousands or even millions of) content providers 180B that can provide textbooks and related materials for content hosting system 110. In some embodiments, reader module 181 and browser 182 include a content player (e.g., Flash™ from Adobe Systems, Inc.), or any other player adapted for the content file formats used by the content hosting system 110.

User computer 180A with reader module 181 is used by users to purchase or otherwise obtain, and access, materials provided by the content hosting system 110. Content provider computer 180B is used by content providers to create and provide material for the content hosting system 110. A given computer can be both a client computer 180A and content provider computer 180B, depending on its usage. The hosting service 110 may differentiate between content providers and users in this instance based on which front end server is used to connect to the content hosting system 110, user logon information, or other factors.

The content hosting system 110 comprises a user front end server 140 and a content provider front end server 150 each of which can be implemented as one or more server class computers. The content provider front end server 150 is connected through the network 170 to content provider computer 180B. The content provider front end server 150 provides an interface for content providers to create and manage materials they would like to make available to users. The user front end server 140 is connected through the network 170 to client computer 180A. The user front end server 140 provides an interface for users to access material created by content providers.

The content hosting system 110 is implemented by a network of server class computers that can include one or more high-performance CPUs and 1 G or more of main memory, as well as 500 GB to 2 Tb of storage. An operating system such as LINUX is typically used. The operations of the content hosting system 110, front end 140 and back end 150 servers as described herein can be controlled through either hardware (e.g., dedicated computing devices or daughter-boards in general purpose computers), or through computer programs installed in computer storage on the servers of the system 110 and executed by the processors of such servers to perform the functions described herein. One of skill in the art of system engineering and, for example, video content hosting will readily determine from the functional and algorithmic descriptions herein the construction and operation of such computer programs.

The content hosting system 110 further comprises a system database 130 that is communicatively coupled to the network 170. The system database 130 stores data related to the content hosting system 110 along with user and system usage information.

The system database 130 can be implemented as any device or combination of devices capable of persistently storing data in computer readable storage media, such as a hard disk drive, RAM, a writable compact disk (CD) or DVD, a solid-state memory device, or other optical/magnetic storage mediums. Other types of computer-readable storage mediums can be used, and it is expected that as new storage mediums are developed in the future, they can be configured in accordance with the descriptions set forth above.

The content hosting system 110 is further comprised of a third party module 120. The third party module 120 is implemented as part of the content hosting system 110 in conjunction with the components listed above. The third party module 120 provides a mechanism by which the system provides an open platform for additional uses relating to electronic textbooks, much as an application programming interface allows third parties access to certain features of a software program. In some embodiments, third party input may be limited to provision of content via content provider computers 180B and content provider front end server 150. Given the wide range of possible operation of system 100, however, in some embodiments it may be desirable to open additional capabilities for third parties who are not providing content to access the system. For example, anonymous use data from groups of students may be made available via third party module 120 to allow tracking of student use of existing textbooks for possible future improvement. As a specific example, aggregated data regarding what sections of a textbook are most often annotated may be helpful to the author of the textbook (or to other authors) to determine where additional explanation of difficult concepts might be warranted.

In this description, the term “module” refers to computational logic for providing the specified functionality. A module can be implemented in hardware, firmware, and/or software. Where the modules described herein are implemented as software, the module can be implemented as a standalone program, but can also be implemented through other means, for example as part of a larger program, as a plurality of separate programs, or as one or more statically or dynamically linked libraries. It will be understood that the named modules described herein represent one embodiment of the present invention, and other embodiments may include other modules. In addition, other embodiments may lack modules described herein and/or distribute the described functionality among the modules in a different manner. Additionally, the functionalities attributed to more than one module can be incorporated into a single module. In an embodiment where the modules as implemented by software, they are stored on a computer readable persistent storage device (e.g., hard disk), loaded into the memory, and executed by one or more processors included as part of the content hosting system 110. Alternatively, hardware or software modules may be stored elsewhere within the content hosting system 110. The content hosting system 110 includes hardware elements necessary for the operations described here, including one or more processors, high speed memory, hard disk storage and backup, network interfaces and protocols, input devices for data entry, and output devices for display, printing, or other presentations of data.

Numerous variations from the system architecture of the illustrated content hosting system 110 are possible. The components of the system 110 and their respective functionalities can be combined or redistributed. For example, the system database 130, third party module 120, user front end server 140, and content provider front end server 150 can be distributed among any number of storage devices. The following sections describe in greater detail the reader module 181, system database 130, and the other components illustrated in FIG. 1 in greater detail, and explain their operation in the context of the content hosting system 110.

Reader Module

FIG. 2 illustrates a functional view of a reader module 181 used as part of a electronic textbook system. In the embodiment described above in connection with FIG. 1, the reader module is implemented on user computer 180A, but it should be recognized that in other embodiments, portions discussed herein could also be implemented on other computers (e.g., those in content hosting system 110) that are in communication with reader module 181.

Reader module 181 is configured to address the fact that students use textbooks differently than other readers use typical books. Students typically study from, rather than merely read, textbooks. Studying is typically less linear than other reading, as texts are rarely read in “start-to-finish” manner. Studying is often much more interactive than typical reading, with annotations, cross-referencing between problem sets and main portions, reference to glossary or definitions sections, and the like. Studying is also inherently social and collaborative as well—far more so than most other types of reading. Learning in general, and studying in particular, typically combines attention to textbooks with creation and reference to notebooks, problem sets, lab experiment results, lecture materials, and other related sources.

Reader module 181 includes various subsystems to facilitate the specialized uses students make of textbooks. In the embodiment illustrated in FIG. 2, reader module 181 includes an annotation subsystem 220, an OCR subsystem 230, a collaboration subsystem 240, an ordering subsystem 250, an input recognition subsystem 260, and a daemon subsystem 270. Many of these subsystems interact with one another, as described below.

Annotation subsystem 220 provides various user tools and interfaces to allow students to mark up portions of an electronic textbook as they may find most helpful for learning and studying purposes. Annotation subsystem 220 includes conventional features such as highlighting and text entry tools, and also includes more advanced tools. For example, as described below annotation subsystem 220 keeps track of textbook portions for which a student has provided annotations, and collects those portions into a personalized study guide based on a user command.

OCR subsystem 230 is a recognition subsystem that takes information not originally in one form and converts it into a second form by recognizing patterns and/or known symbols. For example, OCR subsystem 230 communicates with annotation subsystem 220 to convert handwritten student notes (entered graphically via finger or stylus gestures on a touch screen, for instance) into machine readable text. As used here, the term “OCR subsystem” includes not only optical character recognition, but other types of recognition as well, for instance: voice-to-text recognition to allow a student to speak rather than write annotations; image to text recognition for photographs the student may take of a professor's notes on a blackboard during a lecture; and other types of recognition as well that may be provided within an electronic textbook or as a third party add-on. As a specific example, one type of recognition that may be helpful in a music theory class is recognition of a sound (a melody) and translation into a visual score (sheet music) for that melody.

Collaboration subsystem 240 provides various user functions that allow students to work together. As detailed below, for example, users can share their annotations and notes with their study group, their entire class, or other users worldwide of their electronic textbook. Further, collaboration subsystem 240 includes social network facilities to permit students to undertake study sessions with audio and visual chat, to ask and answer questions, and to submit questions to professors or teaching assistants.

Ordering subsystem 250 represents tools that allow students to obtain electronic textbooks and related materials. In one embodiment, ordering subsystem 250 is implemented as an electronic marketplace (e.g., the Droid™ marketplace implemented on the Android™ operating system for smart phones and tablet computers). Third parties offer electronic textbooks and related materials such as study guides, problem sets, updates, workbooks, and the like. Some of these materials are available for purchase; others are free. In some embodiments, provision via other mechanisms (e.g., subscription, barter, “pay-per-view”) is supported, as may be desired by any subset of a student community or content provider group.

Input recognition subsystem 260 provides user interface tools to facilitate use of electronic textbooks and related features. For instance, by sensing particular gestures on a touch screen of user computer 180A, the system temporarily shifts display of a textbook from a current page to a new section, while keeping track of the section of primary interest. Thus, a student working on a problem set section of the textbook can quickly look back at the text of the chapter, or a student reading a section for the first time can quickly jump to a glossary section of the textbook for a definition of an unfamiliar term or concept.

Reader module 181 is configured to permit user-selected applications to run to enhance a student's ability to work with an electronic textbook. For example, a student may purchase an application that provides study questions on a per-chapter basis for textbooks that do not include such questions. In addition, reader module 181 includes a daemon subsystem 270 to provide additional add-on features without the user launching a visible application for such features. As one example, a music student may have one or more daemons that allow recognition of images of sheet music and audio playback of the corresponding music, or that recognize particular melodies that may be captured by a microphone associated with user computer 180A, or that synthesize musical compositions based on a student's input.

System Database

FIG. 3 illustrates a functional view of the system database 130 that stores data related to the textbook content hosting system 110. The system database 130 may be divided based on the different types of data stored within. This data may reside in separate physical devices, or it may be collected within a single physical device.

With respect to content providers, partner data 370 comprises information regarding content providers, or partners, registered with the content hosting system 110 that have permission to create and deliver content. Partner data 370 includes provider contact information.

For providers creating paid textbooks or other content, partner data 370 contains billing and revenue sharing information for the provider. Some providers may create subscription channels while others may provide single payment or free delivery of electronic textbooks and related information. These providers may have specific agreements with the operator of the content hosting system 110 for how revenue will flow from the content hosting system 110 to the provider. These specific agreements are contained in the partner data 370.

Alternatively, some providers may not have specific agreements with the operator of the content hosting system 110 for how revenue will flow from the content hosting service 110 to the provider. For these providers, partner data 370 comprises a standardized set of information dictating how revenue will flow from the content hosting system 110 to the providers. For example, for a given partner, the partner data may indicate that the content hosting system 110 receives 25% of the revenue for an item provided to a user, and the content provider receives 75%. Of course other more complex allocations can be used with variable factors based on features, user base, and the like.

User profile data storage 310 includes information about an individual user (e.g., a student), to facilitate the payment and collaborative aspects of system 100. Subscriber data storage 320 includes identifying information about the student, such as the electronic textbooks the student has obtained and the social network groups the student has joined. In some embodiments, subscriber data storage 320 also maintains information regarding the location in each of the student's textbooks, where the student is or was reading, to allow, for example, a student to read part of a textbook chapter on a smart phone while on a campus bus and continue reading from the same spot on the student's desktop computer in a dorm room. Subscriber data storage 320 contains, in some embodiments, data about the user that is not explicitly entered by the user, but which is tracked as the user navigates through textbooks and related materials. Subscriber viewing data includes, for example, user study habits, such as the total time spent by the subscriber per chapter, average time spent per week in a textbook, proportion of time spent on initial reading as opposed to problem-set activity and pre-test review, and the like. Such information is in some embodiments made available to the student to assist in tracking and improving study habits; in other embodiments aggregated information is used to help determine how best to improve textbooks and related materials.

Account data storage 330 keeps track of the user's payment mechanisms (e.g., Google Inc.'s Checkout®) related to the user's ability to obtain content from system 100.

Social network data storage 340 maintains the information needed to implement a social network engine to provide the collaborative features discussed herein, e.g., social graphs, social network preferences and rules.

Textbook data 350 stores the actual content that is provided to users upon their request, such as electronic textbook files.

Add-on data storage 360 maintains information for related features, such as non-static data relating to textbooks (e.g., climatological data that could be used by students in connection with an environmental studies textbook).

In one embodiment, conventional mechanisms are used to implement many of the aspects of system database 130. For example, the existing mechanisms from Google Inc.'s Books™ Gmail™, Buzz™ Chat™, Talk™, Orkut™, Checkout™, Youtube™, Scholar™, Blogs™ and other products include aspects that can help to implement one or more of storage facilities 310, 320, 330, 340, 350, 360 and 370 as well as modules 220, 230, 240, 250, 260 and 270. Google Inc. already provides eBook readers for ANDroid™ devices (phones, tablets, etc.), iOS devices (iPhones®, iPads® and other devices from Apple, Inc.) and various desktop Web browsers, and in one embodiment Google Inc.'s Editions™ eBook reader application is modified to provide the functionality described herein.

As mentioned above, user profile data 310 is usable on a per-student basis and is also capable of being aggregated for various populations of subscribers. The population can be the entire subscriber population, or any selected subset thereof, such as targeted subscribers based on any combination of demographic or behavioral characteristics, or content selections. System-wide usage data includes trends and patterns in usage habits for any desired population. For example, correlations can be made between electronic textbooks and add-ons that students choose (presumably related in some way to those textbooks). In one embodiment, when a user obtains a new textbook, such data are used to recommend other related items the user might also be interested in obtaining Valuation of items, relative rankings of items, and other synthesized information can also be obtained from such data.

Bibliographic Reference Detection in Electronic Books

Books, including electronic books, routinely include bibliographies, whether for the entire book or on a chapter-by-chapter basis, as well as in-line references to external works. In one embodiment, for electronic textbooks that do not natively provide links to such sources, OCR subsystem 230 of reader module 181 automatically recognizes patterns indicative of such references, and searches for links to digital versions of these other works. In other embodiments different approaches are utilized within a recognition subsystem to identify bibliographic references in text. In some embodiments, such links are analogous to web hyperlinks, but instead are specialized links that point directly to versions of such other works that are in a form most usable with reader module 181. For example, in one such embodiment a link launches a browser and points it directly at a book in Google Inc.'s Books™, Google Inc.'s Ebookstore™, Amazon.com® or other appropriate source.

In another instance, a link points directly to an add-on in a marketplace, a scholarly article in Google Inc.'s Scholar™ facility, or a patent in Google Inc.'s Patents™ facility, as appropriate. The student is provided, by reader module 181, the ability to access such sources merely by tapping or clicking on the text book portion corresponding to that link. In some cases, the external sources may be free (e.g., works for which copyright has expired) and the student is then shown the link immediately. In other instances, the student is brought to the appropriate vendor store site from which a digital version of the reference may be purchased. Not only other books and journal articles, but patents and other public documents such as court decisions and filings with the Securities and Exchange Commission are made available to students in an extremely efficient manner by such links. In one embodiment, paid content providers offer payment (e.g., a “reward”) to the textbook author, the operator of hosting system 110, or other related parties for purchases facilitated by these links.

In one embodiment the student is automatically directed to a preferred source selected by ordering subsystem 250 from which to obtain a digital copy of a referenced work. In another embodiment the student is directed to a list of sources that can provide the referenced work and prompted to select one from which to obtain a digital copy. In a further embodiment, the student is automatically directed to a preferred source but reader module 181 is configured to provide controls with which the student can override the automatic selection made by ordering subsystem 250 and select from a list of alternate sources.

In some embodiments, ordering subsystem 250 selects a preferred source from which to obtain a digital copy of a referenced work by comparing the price charged by a plurality of sources. In other embodiments other factors and/or combinations of factors are used by ordering subsystem 250 to select the preferred source, such as user preferences, terms of use for the digital copy, the format of the digital copy, and feedback provided by other users.

Additional Considerations

Some portions of above description describe the embodiments in terms of algorithms and symbolic representations of operations on information. These algorithmic descriptions and representations are commonly used by those skilled in the data processing arts to convey the substance of their work effectively to others skilled in the art. These operations, while described functionally, computationally, or logically, are understood to be implemented by computer programs executed by a processor, equivalent electrical circuits, microcode, or the like. Furthermore, it has also proven convenient at times, to refer to these arrangements of operations as modules, without loss of generality. The described operations and their associated modules may be embodied in software, firmware, hardware, or any combinations thereof.

As used herein any reference to “one embodiment” or “an embodiment” means that a particular element, feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.

As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, “or” refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

In addition, use of the “a” or “an” are employed to describe elements and components of the embodiments herein. This is done merely for convenience and to give a general sense of the invention. This description should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise.

Upon reading this disclosure, those of skill in the art will appreciate still additional alternative structural and functional designs for a system and a process for providing electronic textbooks using a content hosting system through the disclosed principles herein. Thus, while particular embodiments and applications have been illustrated and described, it is to be understood that the disclosed embodiments are not limited to the precise construction and components disclosed herein. Various modifications, changes and variations, which will be apparent to those skilled in the art, may be made in the arrangement, operation and details of the method and apparatus disclosed herein without departing from the spirit and scope defined in the appended claims. 

1. An electronic book reader comprising: a recognition subsystem, configured to identify a pattern of characters within a portion of text indicative of the characters representing a bibliographic reference to an external work; and an ordering subsystem, configured to provide a digital copy of the external work responsive to selection of the bibliographic reference by a user.
 2. The electronic book reader of claim 1, wherein the recognition subsystem is an optical character recognition (OCR) subsystem.
 3. The electronic book reader of claim 1, wherein the ordering subsystem is further configured to automatically select a preferred source of the external reference responsive to one or more factors.
 4. The electronic book reader of claim 3, wherein the one or more factors includes at least one of: terms of delivery provided by the preferred source, preferences set by the user, format in which the external work is provided by the preferred source, and feedback provided by other users.
 5. The electronic book of claim 4, wherein the terms of delivery include a price.
 6. The electronic book of claim 4, wherein the terms of delivery include terms of use.
 7. The electronic book reader of claim 1, wherein the order subsystem is further configured to direct the user to an on-line marketplace for the digital copy.
 8. The electronic book reader of claim 1, wherein the digital copy is provided for free.
 9. The electronic book reader of claim 1, wherein the user makes a payment in exchange for the digital copy.
 10. The electronic book reader of claim 9, wherein the payment is automatically split between two or more parties.
 11. A computer-implemented method for identifying and using bibliographic references in an electronic book, comprising: identifying a pattern of characters within a portion of text indicative of the characters representing a bibliographic reference to an external work; and providing a digital copy of the external work responsive to selection of the bibliographic reference by a user.
 12. The method of claim 11, further comprising automatically selecting a preferred source of the external work responsive to one or more factors.
 13. The method of claim 12, wherein the one or more factors includes at least one of: terms of delivery provided by the preferred source, preferences set by the user, format in which the external reference is provided by the preferred source, and feedback provided by other users about the source.
 14. The method of claim 13, wherein the terms of delivery include a price.
 15. The method of claim 13, wherein the terms of delivery include terms of use.
 16. The method of claim 11, wherein providing a digital copy includes directing the user to an on-line marketplace.
 17. The method of claim 11, wherein the digital copy is provided for free.
 18. The method of claim 11, further comprising making a payment in exchange for the digital copy.
 19. The method claim 18, wherein the payment is automatically split between two or more parties.
 20. A computer program product that comprises a non-transient computer readable storage medium containing computer executable instructions for identifying and using bibliographic references in an electronic book, comprising: instructions to identify a pattern of characters within a portion of text indicative of the characters representing a bibliographic reference to an external work; and instructions to provide a digital copy of the external work responsive to selection of the bibliographic reference by a user.
 21. The computer program product of claim 20, further comprising instructions to automatically select a preferred source of the external work responsive to one or more factors.
 22. The computer program product of claim 21, wherein the one or more factors includes at least one of: terms of delivery provided by the preferred source, preferences set by the user, format in which the external reference is provided by the preferred source, and feedback provided by other users about the source.
 23. The computer program product of claim 22, wherein the terms of delivery include a price.
 24. The computer program product of claim 22, wherein the terms of delivery include terms of use.
 25. The computer program product of claim 20, wherein the instructions to provide a digital copy include instructions to direct the user to an on-line marketplace.
 26. The computer program product of claim 20, wherein the digital copy is provided for free.
 27. The computer program product of claim 20, further comprising instructions to make a payment in exchange for the digital copy.
 28. The computer program product claim 27, wherein the payment is automatically split between two or more parties. 